EX Squared Solutions Interview Questions and Answers

Coderbyte platform was used
There were 3 easy problems related to string and array manipulation and 2 medium to hard problems of lru cache implementation and the other one was of the time difference between the given 12hour format time (it was given in string) and there was a sql hard question in which it asked us to filter the table based on the given conditions and add a column with a given condition

Q1. They asked me reverse of linked list and rotate a matrix by 90 degeress questions and they asked basic oops concepts and some basic sorting algorithms they asked me to explain the merge sort then they aske...read more
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Round duration - 60 minutes
Round difficulty - Easy

Q1. 
Pair Sum Problem Statement
You are provided with an array ARR consisting of N distinct integers in ascending order and an integer TARGET. Your objective is to count all the distinct pairs in ARR whose sum...read more
Ans. 
Count distinct pairs in a sorted array that sum up to a given target value, returning -1 if no pairs exist.
• Two-Pointer Technique: Use two pointers, one at the start and one at the end of the array, to find pairs efficiently.

• Distinct Elements: Since the array contains distinct integers, each valid pair will be unique.

• Example: For ARR = [1, 2, 3] and TARGET = 4, the only pair is (1, 3).

• Return Value: If pairs are found, r...read more
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Q2. 
Maximum Sum Path from Leaf to Root
Given a binary tree with 'N' nodes, identify the path from a leaf node to the root node that has the maximum sum among all root-to-leaf paths.
Example:
All the possibl...read more
Ans. 
Find the maximum sum path from a leaf node to the root in a binary tree using level order input.
• Input Format: The binary tree is represented in level order, with '0' indicating null nodes.

• Example: For input '4 -2 3 4 0 5 6 0 7 0 0 0 0 0 0', the tree structure can be visualized.

• Path Calculation: Traverse the tree recursively to calculate the sum of paths from leaves to the root.

• Output: Return the path with the maximum s...read more
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Q3. Write an SQL query to fetch records that are present in one table but not in another table.
Ans. 
SQL query to find records in one table that do not exist in another table using LEFT JOIN or NOT EXISTS.
• LEFT JOIN: Use a LEFT JOIN to combine both tables and filter where the second table's key is NULL. Example: SELECT a.* FROM TableA a LEFT JOIN TableB b ON a.id = b.id WHERE b.id IS NULL.

• NOT EXISTS: Use a subquery with NOT EXISTS to check for non-existence. Example: SELECT * FROM TableA a WHERE NOT EXISTS (SELECT 1 FR...read more
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Round duration - 30 minutes
Round difficulty - Easy

Q1. 
Convert Sentence to Pascal Case
Given a string STR, your task is to remove spaces from STR and convert it to Pascal case format. The function should return the modified STR.
In Pascal case, words are con...read more
Ans. 
Convert a given string to Pascal case by removing spaces and capitalizing the first letter of each word.
• Input Handling: Read the number of test cases and each string to be processed.

• String Manipulation: Split the string by spaces, capitalize each word, and join them without spaces.

• Example: 'hello world' becomes 'HelloWorld'.

• Efficiency: Ensure the solution handles up to 500,000 characters efficiently due to constraints.
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Round duration - 60 Minutes
Round difficulty - Easy

Q1. 
Buy and Sell Stock Problem Statement
Imagine you are Harshad Mehta's friend, and you have been given the stock prices of a particular company for the next 'N' days. You can perform up to two buy-and-sell ...read more
Ans. 
Maximize profit from stock prices over N days with up to two buy-and-sell transactions.
• Two Transactions: You can buy and sell stocks twice to maximize profit.

• Sell Before Buy: Ensure you sell a stock before buying again.

• Example 1: Prices = [3, 3, 5, 0, 0] yields max profit of 6.

• Example 2: Prices = [7, 6, 4, 3, 1] yields max profit of 0.

• Dynamic Programming: Use dynamic programming to track profits efficiently.
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Q2. 
Generate Possible Words from T9 Keypad
Given a string S consisting of digits from 2 to 9, the task is to generate all possible strings that can be formed by mapping these digits to letters on a T9 keypad....read more
Ans. 
Generate all possible letter combinations from a T9 keypad input string, sorted lexicographically for each test case.
• Mapping Digits: Each digit from 2 to 9 corresponds to specific letters (e.g., 2 -> 'abc', 3 -> 'def').

• Combination Generation: Use backtracking or iterative methods to generate all possible combinations of letters for the given digits.

• Lexicographical Order: Ensure the output combinations are sorted ...read more
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Round duration - 60 Minutes
Round difficulty - Medium

The test was conducted around 3 pm . Four coding questions were there. 2 questions were easy and 2 were of moderate difficulty level. It was conducted remotely with video proctoring.I was able to solve all the 4 questions.

Q1. 
Generate Possible Words from T9 Keypad
Given a string S consisting of digits from 2 to 9, the task is to generate all possible strings that can be formed by mapping these digits to letters on a T9 keypad....read more
Ans. 
Generate all possible strings by mapping digits to letters on a T9 keypad and print them in lexicographical order.
• Create a mapping of digits to letters on a T9 keypad

• Use recursion to generate all possible combinations of letters for the given digits

• Sort the generated strings in lexicographical order

• Return the sorted strings as an array of strings
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Q2. 
Flip Bits Problem Explanation
Given an array of integers ARR of size N, consisting of 0s and 1s, you need to select a sub-array and flip its bits. Your task is to return the maximum count of 1s that can b...read more
Ans. 
Maximize the count of 1s in a binary array by flipping a sub-array of 0s to 1s at most once.
• Initial Count: Start by counting the number of 1s in the original array.

• Flipping Logic: For each sub-array, calculate the effect of flipping 0s to 1s and 1s to 0s.

• Kadane's Algorithm: Use a modified version of Kadane's algorithm to find the maximum gain from flipping a sub-array.

• Edge Cases: Consider cases where the array is all 1...read more
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Round duration - 10 Minutes
Round difficulty - Easy

It was a telephonic round. The HR asked some basic questions like how was your experience in the previous rounds.
 

Q1. Why do you want to join our company and why should we hire you?
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